This invention relates to a brake device for a drafting parallel, and more particularly to a manually adjustable brake device capable of preventing unwanted movement of a drafting parallel resting upon the surface of a tiltable drafting table.
On certain types of draftsman's tables which are adapted to be inclined at various angles, a drafting parallel is provided which lies flat against the working surface of the table and is adjustably positionable thereon by sliding engagement with guide means associated with at least one side edge of said surface and perpendicular to said drafting parallel. The drafting parallel is mechanically coupled to said guide means with the aid of a continuous cable which traverses said drafting parallel in two passes in close parallel adjacency. The cables are generally housed between a lower member of said drafting parallel which lies flat against the table surface, and a cover which extends along the upper surface of said lower member.
A commonly encountered problem with a drafting parallel of the aforesaid nature is that it tends to fall to lower positions on the table surface due to the effect of gravity, said falling being more pronounced with steeper inclinations of said table surface.
Although brake devices have been disclosed for preventing the falling motion of the drafting parallel, such devices have been either of complex and expensive design, or difficult to manipulate in the course of usual drafting manipulations. Other brake devices require structural modification of the parallel to facilitate installation. Although such devices may be incorporated into a parallel during the manufacture thereof in a factory, they are not easily applied to existing parallels.
It is accordingly an object of the present invention to provide a brake device of simple construction and facile operation which will controllably lock the position of a drafting parallel on a tiltable drafting table.
It is another object to provide a device of the aforesaid nature which can be readily installed onto a drafting parallel of common design without structural modification thereof.
It is a still further object of this invention to provide a device of the aforesaid nature capable of manual operation and of a size sufficiently small to avoid impairment of the general functionality of said drafting parallel.
These objects and other objects and advantages of the invention will be apparent from the following description.